Draft EIS_072312.pdf - Middle Fork American River Project ...

20120723-4002 FERC PDF (Unofficial) 07/23/2012
long enough time to adequately assess the effects of the vegetation and pest management
program.
Monitoring Methylmercury Concentrations of Sportfish in Project Waters
Hell Hole reservoir, Ralston afterbay, and the North Fork American River are on
the current 303(b) list of impaired waters for mercury (Water Board, 2012). The source
of mercury in Hell Hole reservoir is listed as unknown, but the likely source for the other
two waterbodies is listed as resource extraction. PCWA documented during relicensing
studies elevated levels of methylmercury in fish tissue in French Meadows reservoir, Hell
Hole reservoir, Middle Fork interbay, Ralston afterbay, and the Middle Fork American
River at Otter Creek, as well as in crayfish in Hell Hole and French Meadow reservoirs.
The source of the methylmercury in the Middle Fork American River watershed is likely
not related to project operations or facilities. PCWA proposes to implement a Mercury
Bioaccumulation Monitoring Plan that would provide data characterizing methylmercury
concentrations in the muscle tissue of sportfish from French Meadows reservoir, Hell
Hole reservoir, Ralston afterbay, and the Middle Fork American River near Otter Creek.
Monitoring would be conducted every 5 years for the term of the license beginning 3
years after the license is issued. Methylmercury concentrations would be compared with
OEHHA and/or EPA screening value guidelines for methylmercury (Cal/EPA, 2005;
Klasing and Brodberg, 2006).
Forest Service 4(e) condition no. 28 includes the Mercury Bioaccumulation
Monitoring Plan among the plans that still need to be finalized. The Forest Service did
not indicate if and what issues remained to be resolved to finalize the Mercury
Bioaccumulation Monitoring Plan. Therefore, for the purposes of our analysis, we
assume the Alternative 1 plan would essentially be the same as PCWA’s plan with the
potential for additional minor modifications to occur.
Our Analysis
Elevated methylmercury levels in fish tissue have been reported throughout the
Sierra Nevada region and have often been linked to historical mining activities, although
they may also be attributable to natural causes, including geologic and atmospheric
conditions. We do not expect any changes to project operations made as part of the
proposed action or Alternative 1 to have any effect on methylmercury levels in fish in the
project area. Methylmercury concentrations in fish tissue are likely to remain high in the
future. Implementation of the proposed Mercury Bioaccumulation Monitoring Plan
would track levels of methylmercury in sportfish and provide information to appropriate
agencies on whether issuing health advisories for anglers at project waters is warranted.
However, PCWA does not propose any substantive changes to project reservoir levels.
Therefore, we do not expect any changes in methylmercury concentration levels in
sportfish as a result of project operations.
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